Capsule The Ring Ouzel has declined to near extinction on the island of Ireland, with just nine occupied sites recorded during a national survey in 2021, all in County Donegal in north-west Ireland.Aims Little is known about the status and population trends of the Ring Ouzel in Ireland. The aim of the 2021 survey in the Republic of Ireland was to determine its current breeding population size and range.Methods We identified tetrads that had records of breeding Ring Ouzels in Ireland in the previous 20 years. Using a standard methodology, including playback, we visited tetrads at least twice to record occupancy and evidence of breeding as well as to record habitat associations and land use.Results Ring Ouzels were detected in just nine of 75 tetrads surveyed, with probable/confirmed breeding in four and possible breeding in five tetrads, all in County Donegal in north-west Ireland. Habitats at Ring Ouzel breeding sites (139-530 m a.s.l.) were predominantly dry heath, blanket bog and scree. Sheep Ovies aries grazing (in 87% of tetrads) was the most widespread land use.Conclusion The Ring Ouzel is in imminent risk of extinction in Ireland, after the loss of the breeding population in County Kerry in south-west Ireland within the last decade, and a tiny, remnant population now confined to north and south-west Donegal. The conversion of heath to grass moorland appears to be an important factor driving the decline in Ireland. Climate change effects, such as drier summers, may also be impacting the accessibility and availability of invertebrate prey. Urgent conservation actions are needed to halt further decline to extinction, especially in the few remaining breeding areas.
Capsule Operator errors when taking morphometric measurements are more important for larger species and for mass measurements.Aims To quantify operator effects on morphometric measurements during ringing sessions, depending on species size and morphometric characters.Methods Three morphometric characters (wing length, body mass and body condition index) had been measured during ringing sessions on 17,818 individuals of 14 different species in southern France. The deviation from the mean and the variation, both absolute and by percentage, of measurements taken by operators were estimated for each bird species and age and sex categories.Results We detected operator effects on measurements. Wing length showed a deviation from the mean, reaching less than 1% of total measurement and a small variation. However, body mass showed a large deviation from the mean, and a large variation reaching up to 10% of total measurement. Body condition index showed broadly the same results as body mass, with the same proportion. Larger species were the most affected by measurement errors, both in absolute and in percentage terms.Conclusion Errors in morphological measurements are common during ringing sessions and are related to the characteristics of the species, particularly their size, the tools used (such as dynamometers for body mass) and the characteristics of the operators.
Capsule Artificial nests are often used in ecological studies, but our research on Estonian coastal grasslands shows they differ significantly from natural nests in predation rates and predator identity, highlighting the importance of studying natural nests whenever possible.Aims Artificial nests may serve as an alternative to natural ones in studies of nest predation, but it is crucial to evaluate their suitability within specific local contexts.Methods We conducted a comparative analysis of daily survival rates between artificial and natural nests of waders in coastal grassland habitat in Estonia over two breeding seasons. Additionally, we employed camera traps to identify predators on a subset of nests.Results Our findings reveal discrepancies in nest survival and observed predators between artificial and natural nests, as well as annual differences. These results indicate that, at least in our study area, artificial nests are not an adequate substitute for natural nests when studying nest survival or when identifying nest predators.Conclusions Consistent with previous authors' conclusions, we encourage ornithologists to invest time and effort in locating and studying natural nests whenever it is feasible to do so.
Capsule Individual Common Swifts show high fidelity to nest sites (94-95%), and lesser fidelity to partners (59%).Aims To determine the extent of individual fidelity to nest sites and partners by Common Swifts, and to identify any predictors of nest site fidelity.Methods We monitored nest boxes and captured adult Common Swifts over the 15-year period 2010-2024. Fidelity analyses were based on 243 breeding events and capture data from 190 adults matched to nest sites and pairings. Predictors of nest site fidelity were examined using logistic regression.Results From 243 breeding events, 91 individuals bred in multiple years. Across 216 breeding events involving at least one breeding individual captured in multiple years, 94.5% re-used a previously used nest site. Among 213 breeding events involving an individual captured in consecutive years, 94.3% re-used the previous year's nest site. Nest site fidelity between consecutive years was significantly lower at higher colony densities, but was not predicted by individual age or previous breeding success. Of 36 consecutive year pairings involving the same two individuals, 89% re-used the same nest site. Among 168 breeding events where both pair members were identified, 39 unique pairings bred together in multiple years. Of 55 consecutive year pairings, 94.5% remained faithful and 5.5% divorced.Conclusions Common Swifts are declining in the UK, with nest site loss being a hypothesized contributory factor. We show that breeding swifts have very high rates of fidelity to nest sites and partners, and hence colonies, and the loss of nest sites is therefore likely to have impacts on individuals and colonies due to the need to find alternatives. We provide some evidence of local relocation by breeding individuals after nest site loss, suggesting that local provision of nest sites may help maintain local populations.
Capsule: An assessment of the utility of deploying trail cameras to describe the timing of breeding and habitat selection by Corncrakes. Aims: To estimate the hatching dates of broods of Corncrake chicks, and the timing of occurrence of juvenile birds, and to compare the intensity of use of two distinct habitats. Methods: Trail cameras deployed in and adjacent to agricultural grassland managed for silage production and livestock grazing captured images of Corncrakes. Young of the year were aged using plumage characteristics. Hatching dates and the timing of breeding were compared with expectations from a previous simulation modelling study based on radio-tracking, and observations of broods during mowing. Intensity of use (calculated as the number of days on which images were obtained per day of camera deployment) was compared between previously-mowed, initially short, habitat and taller early cover habitat. Results: Timing of breeding indicated by the camera study was broadly similar to that expected from previous studies using other methods. The intensity of use of early cover habitat by young of the year remained higher throughout summer than that of initially short habitat, even though the latter increased in height substantially during the breeding season. Conclusion: Trail cameras have considerable potential for studies of the timing of breeding and habitat selection by Corncrakes, whose chicks and females are difficult to mark with tracking tags, and whose secretive habits make searching for nests and broods and other direct visual monitoring methods impractical. This approach could be applied to other species with secretive habits. The design of camera surveys, including ours, would benefit from improved stratified sampling and optimisation of camera densities in different habitats. Preliminary results suggest that Corncrake conservation would benefit from increasing the proportion of land that is managed to produce tall, early cover vegetation, rather than grassland mowed for silage.
Capsule: Human activity on a river significantly influenced the behaviour of urban Eurasian Coots outside the breeding season, as the birds spent more time swimming in response to boat traffic. Aims: Urbanization is associated with a range of environmental changes that influence animal behaviour. Urban animals respond to anthropogenic disturbances in various ways; however, their first visible response is typically behavioural, resembling antipredator reactions such as fleeing. I assessed the effects of human activities and environmental variables on multiple behavioural traits in Eurasian Coots wintering in the centre of a densely populated city (Belgrade, Serbia). Methods: Using multivariate models, I examined the effects of anthropogenic disturbance, air temperature, wind speed, time of day and flock size on several categories of Eurasian Coot behaviour simultaneously. Results: Focal birds devoted different proportions of time to different activities, depending on anthropogenic disturbance, air temperature, wind speed, time of day and flock size. Exposure to boat traffic increased the time that Eurasian Coots spent swimming. Feeding activity declined around midday and was negatively associated with wind speed; self-maintenance behaviour increased with rising air temperature, while swimming activity decreased with flock size. Conclusion: This study provides evidence that anthropogenic disturbance negatively affected the behaviour of urban Eurasian Coots, which spent more time swimming at the expense of fitness-enhancing activities, such as feeding and preening.
CapsuleUpper Teesdale in northern England supported 1,764 pairs of Eurasian Curlews (95% CL: 1,486-2,145), representing approximately 3% of the UK population; successful breeding and repeat counts indicated recent stable numbers.AimsTo estimate breeding numbers by extrapolating from habitat-specific densities, nesting success (including three other wader species) from camera traps and population status from repeat counts.MethodBirds were surveyed using transect-based methods in six habitat types within 114 1 km & times; 1 km grid squares. Linear densities estimated from transects in each habitat were converted into areal densities by comparing transect results with those from block surveys within the same grid squares. Habitat-specific densities were multiplied by habitat availability in the study area to give habitat-specific totals, which were summed to estimate total population size. Clutch survival was monitored using camera traps. Population status was assessed from repeat surveys approximately 10 years apart.ResultsAll but one surveyed square supported Eurasian Curlews, with densities highest in rough grazing and grass-moor habitats at mid-elevations. Twice as many Eurasian Curlews occurred on blanket bog managed by burning and cutting than on unmanaged bog. Abundance from whole-square searches (block surveys) was 29% higher than from transect surveys in the same squares. Summed habitat-specific totals gave 1,764 pairs. Estimated clutch survival of Eurasian Curlews was 0.51, averaging 0.71 for four wader species combined. The most frequent clutch predators detected were Eurasian Badgers Meles meles, Stoats Mustela erminea and Sheep Ovis aries. Eurasian Curlews fledged 1.0 chick per pair, double the number needed to sustain numbers. Repeat surveys indicated that breeding numbers were stable in recent years at both scales.ConclusionsHigh densities and high breeding success of Eurasian Curlews occurred within connected open-ground upland habitats within designated protected landscapes, where licensed culling of predators and management of blanket bog by gamekeepers to produce Red Grouse Lagopus scotica for recreational shooting, together with wildlife-friendly farming, were widely practised.
CapsuleOver time, the total number of bird species and individuals recorded on bird surveys decreased for older observers, whereas they increased for young observers.AimsWe hypothesized that observer age and sex influence long-term bird survey results, with older observers recording progressively fewer birds, and with women performing better than men. We also assumed that the habitat in which the surveys are conducted plays a role in these effects.MethodsWe used data from 99 sites and a 20-year period of the Austrian Common Bird Monitoring Scheme. We calculated the total number of species and individuals recorded at each site and year. We fitted linear models for each individual site and for both variables, with count year as an independent variable. We then used the resulting slope values in linear mixed-effects models, with observer age, observer sex, habitat and start year as explanatory variables. Finally, we excluded birds with high-pitched songs from the dataset and re-ran the models.ResultsObserver age significantly influenced the linear regressions' slopes of the total number of species and individuals. Young observers produced slight increases, while older observers produced slight decreases. Female observers tended to show increases up to a greater age than males, but this result was not significant, probably due to the small sample size for females. Habitat had no significant influence. When excluding birds with high-pitched songs, the effect sizes approximately halved for both dependent variables.ConclusionWe found proof of observer effects in the analysed data. In relation to age, we concluded that there is an optimum curve, with middle-aged observers causing neither positive nor negative bias in long-term counts. We discuss how learning effects, hearing impairment, other ageing effects or sex-related differences could influence our results. Lastly, we address several options for dealing with observer effects.
Capsule: The landscape mosaic and increased heterogeneity resulting from a severe forest disturbance (windstorm followed by bark beetle outbreak) in Northern Italy increased suitable habitat for the European Nightjar, primarily due to the newly established shrub cover. Aims: In 2024, we investigated the occupancy pattern of the European Nightjar in a forest area in Trentino (Italy) damaged by the Vaia windstorm in 2018 and by a subsequent bark beetle infestation (mainly the Eight-toothed Spruce Bark Beetle Ips typographus). Methods: We conducted point count surveys at 52 points across the 200 ha study area, encompassing a range of different types of environments, including intact forest, pre-existing clearings and windthrows caused by the Vaia storm. Results: We found a positive effect of shrub coverage on European Nightjar occupancy probability, while other storm-related features, e.g. roots and bare ground, had a positive (yet weak) influence. European Nightjars seemed to benefit from the mosaic of landscape features and increased environmental heterogeneity that have emerged in this post-windstorm forest area, which was previously dominated by closed-canopy conifer trees. Conclusions: Future management of the study area and similar sites should consider the ecological opportunities arising from disturbance, and the importance of preserving part of the new clearings with dead wood legacies, in order to build a more resilient and biodiverse forest ecosystem.
CapsuleThe Water Rail breeding population at the Tay Reedbeds, eastern Scotland, is partially migratory.AimsTo investigate the migratory and breeding behaviours of Water Rails in Scotland's Tay Reedbeds.MethodsLight-level geolocators were used to estimate migration timing, identify non-breeding locations and infer breeding behaviour of nine individuals from ten recovered geolocators over a six-year period.ResultsFive breeding birds remained resident year-round, two migrated to Ireland for the winter (including one individual tagged in two years that migrated in both), and two additional birds arrived from north-east Europe to winter in the Tay Reedbeds. Based on incubation periods of >= 19 days as an indicator of success, ten of 15 incubation attempts (67%) were successful. Among the ten bird-years (n = nine individuals, with one bird monitored across two years), 50% of breeding birds were single-brooded, 10% were double-brooded, 20% made a second breeding attempt after a failure, 10% made two failed attempts before a successful one, and 10% made a single unsuccessful attempt.ConclusionThe results indicate that the breeding population of Water Rails in Britain, previously considered resident, is partially migratory. Light-level geolocators can provide valuable insights into breeding ecology, particularly for species where direct observation is challenging.
Bird colonies can provide better protection against predators for other bird species, although negative interspecies interactions are possible. The presence of colonies of small gulls (Laridae) and marsh terns Chlidonias spp. is important for breeding Black-necked Grebes. The clutch size and breeding success of Black-necked Grebes were studied at 18 fishponds in southern Poland, with measurements taken of the distance of a grebe nest to the nearest nests of associated species (Black-headed Gull Chroicocephalus ridibundus or Whiskered Tern Chlidonias hybrida). There was no significant difference in the number of eggs laid between Black-necked Grebe nests located within colonies of gulls or terns. However, grebe nests were significantly farther from tern nests than from gull nests. The breeding success of Black-necked Grebes was significantly higher in Black-headed Gull colonies compared to Whiskered Tern colonies, possibly because the greater aggression of terns was directed at the grebes themselves.
CapsuleThis first detailed investigation into the diet of Little Terns along the North Atlantic coast of Morocco, focusing on the tidal zone of Mansouria over six years, highlights the species' dietary composition during chick-feeding at an important nesting site.AimsTo assess the diet composition and foraging behaviour of Little Terns in the tidal habitat near its breeding site on the Mansouria coast, in Morocco, with a focus on prey diversity and changes the prey species delivered to chicks over time.MethodsFieldwork was conducted over six breeding seasons (2009-2014) in a 38-ha estuarine area (2 km long, 0.3 km wide) near the Moroccan cities of Mohammedia and Bouznika. Data collection included direct visual observations, photographic documentation of foraging behaviour and analysis of prey remains found near nests.ResultsFrom a total of 105 prey items identified, Little Tern chick diet predominantly consisted of fish (n = 93, 88.6%) and arthropods (n = 12, 11.4%). Key fish species identified were European Pilchards (Sardina pilchardus; n = 33, 31.4%), gobies (mainly Gobius niger; n = 20, 19.0%), White Seabreams (Diplodus sargus; n = 16, 15.5%) and sand smelts (Atherina spp; n = 13, 12.4%). Chicks were initially fed small fish, with prey size increasing as the chicks grew.ConclusionThis study provides an initial assessment of Little Tern chick diet in Moroccan coastal waters. While limited to low-tide observations, the findings emphasize the significance of the Mansouria tidal zone as a critical feeding habitat, supporting calls for its conservation.
CapsuleWetlands and lagoons of the Mediterranean region are important wintering areas for some species of raptors that breed in Europe.AimsWe report the abundance, density and habitat choice of raptors wintering in coastal wetlands, lagoons and surrounding habitats of western Greece.MethodsData were collected during roadside surveys. Species abundance was calculated with the kilometric abundance index, while densities were estimated through density surface models.ResultsMarsh Harriers Circus aeruginosus and Common Buzzards Buteo buteo were the most abundant raptors recorded, with the former mostly detected in wetlands and the latter on arable land. Nearly all wintering Marsh Harriers were adult females and immatures. Few Kestrels Falco tinnunculus were detected. A flock of 28 Greater Spotted Eagles Clanga clanga was observed roosting at the Amvrakikos gulf.ConclusionMarsh Harriers and Common Buzzards were the most abundant wintering raptors recorded in Greek coastal wetlands. Few records of Kestrels are consistent with previous suggestions of interspecific competition with Common Buzzards, combined with the greater ability of Common Buzzards to cross water barriers, which may influence their relative wintering distribution in the Mediterranean basin. The importance of Greek coastal wetlands was confirmed as one of the most important wintering areas for the Greater Spotted Eagles in the Mediterranean Basin.
CapsuleSedge Warblers Acrocephalus schoenobaenus that stopover along the Atlantic flyway refuelled at varying rates, depending on age, initial body condition and latitude; refuelling rates were poorly structured among sites, suggesting a broad capacity of birds to exploit various wetlands during stopover.AimsTo test how Sedge Warblers accumulate fuel during stopovers in a major migratory corridor along coastal Atlantic wetlands, from northern France to the Bay of Biscay in Spain, and to identify factors affecting the fuel deposition rate (FDR).MethodsWe analysed 7,149 records of Sedge Warblers captured at least twice within the same site and year, collected over 32 years across 28 wetlands. We used linear mixed models to test the effect of age, initial body mass, date, latitude and habitat structure on FDR. Additionally, we modelled initial body mass as a response variable to examine large-scale variation in the arrival condition of birds, with age, date, latitude and habitat features as predictors.ResultsThe fuel deposition rate declined with increasing initial body mass. The effect of latitude varied with age: for yearlings, refuelling rates increased from north to south, while adults showed relatively constant rates along the flyway. Initial body mass was higher in birds captured later in the season and in those using landscapes with smaller and more fragmented wetlands, but decreased with latitude. Habitat metrics had limited explanatory power.ConclusionSedge Warblers appeared to refuel opportunistically throughout the extensive network of wetlands that spans the Atlantic flyway. This finding reinforces the importance of preserving habitat connectivity along migratory routes and supports a landscape-scale conservation approach that integrates ecological functionality and behavioural flexibility.
In one of the very few investigations of the movements of the Eurasian Hobby, we caught and GPS-tagged two females in north-eastern Poland. Tracked individuals had strikingly different breeding home ranges of 1.5 km2 and 83.2 km(2) and moved, on average, a respective 23 and 61 km per day. On 1 September 2021, both birds began migrating and flew directly south, covering up to 999 km per day, and averaging 276 km for the first female and 327 km for the second. After the birds moved approximately 10,000 km, their signals were lost in central and southern Africa, respectively.
CapsuleWe describe the movements of colour-ringed White-tailed Eagles, observed in later stages of life, from their hatching sites.AimsTo investigate the movement distance of individuals of various ages from their hatching sites in an increasing population, and to study the influence of natal habitat type and possible changes over time.MethodsWe analysed ring recovery data collected between 1988 and 2023 in Lithuania, from 315 local and 74 foreign-ringed White-tailed Eagles and tested the effects of individual age and natal habitat type (coastal and inland) on recovery distance. We also compared recovery distances between 1988-2012 (the early stages of population establishment) and 2013-2023.ResultsWhite-tailed Eagles in Lithuania were recovered, on average, 128 km +/- 209 SD (n = 388) from their ringing locations, and we found no significant differences in recovery distance between immatures (mean 137 km from hatching sites) and adults (mean 111 km). However, outside of Lithuania, immatures showed a southward directional preference compared to adults. Eagles hatched in coastal areas were recovered at significantly shorter distances from their nest sites (mean 51 km) than those hatched inland (mean 215 km). Recovery distances decreased significantly over the last decade, particularly for birds originating from inland habitats.ConclusionFor White-tailed Eagles in Lithuania, the distance between hatching location and recovery sites during the later stages of life was strongly dependent on natal habitat, but not the age of individuals. The almost three-fold decrease in recovery distance in recent years suggests that the growing population is shifting to more localized movements within the region. Our study highlights the role of natal habitat quality and/or population density in shaping movement behaviour and suggests potential future implications for population dynamics, habitat occupation and inter-species interactions within the region.
Capsule:Camera and automated image analysis technologies offer one solution to the challenges of seabird monitoring; however, their application is often not straightforward and there is currently unlikely to be a universally applicable method across sites and species.Aims:Evaluate a range of time-lapse camera and automated image analysis methods to monitor seabirds in various coastal settings. Provide recommendations and guidelines on the minimum equipment needed to obtain representative information from time-lapse images.Methods:To establish an efficient and effective method to generate count and/or presence/absence data from images of seabirds, we assess the application of two image analysis methods: (1) bespoke and site-specific object detection, and (2) open-source and generalised object detection. Using a worked example of time-lapse photography of three coastal seabird roosts, we compare data from each image analysis method, evaluating performance and overall success relative to manually collected data from the same images.Results:When detecting seabird presence/absence, we found no consistency in image analysis performance (3.2-94.7% correct detection of true presence; 9.8-98.2% correct detection of true absence). When generating counts, the performance of the different approaches varied (6.3-37.5% of automated counts were correct, relative to manual counts). Notably, whilst the bespoke method was the most successful when generating counts, both object detection methods consistently underestimated seabird abundance.Conclusions:Bespoke, site-specific analyses could be required where count data are needed, whereas open-source generalized detection methods may be suitable where presence/absence data are sufficient to meet study aims. Automating image analysis is unlikely to remove the need for manual analysis, whether to produce training data sets, validate output, and/or compliment observations. By offering lessons learnt from a worked example and resultant recommendations, this study informs future projects aiming to use inexpensive and accessible image technologies for ecological research.
CapsuleLong-term monitoring revealed density-dependent regulation of a recovering population of White Storks in northern Spain.AimTo analyse long-term changes in the population size, productivity and colony dynamics of the White Stork at the northern edge of its breeding range in Spain.MethodsWe used breeding data from 1948 to 2024 to obtain population trends, reproductive output and spatial nesting patterns (proportion of isolated versus colonial nests, and nest substrate) in & Aacute;lava, in northern Spain.ResultsThe population showed a three-phase trajectory: a decline until the early 1980s, followed by a rapid growth through the 2010s, followed by a recent stabilization or slight decline. Colony formation increased with population size, indicating a density-related response, although colonial nesting did not improve reproductive success. Productivity declined with increasing population size and over time, and was higher in nests with presumed site fidelity.ConclusionOur findings suggest that density-dependent factors were now regulating this White Stork population, consistent with patterns reported in other parts of Europe. Anticipated reductions in food availability from landfill closures could limit future population growth. Long-term data are essential to understand population dynamics and to guide adaptive conservation in changing landscapes.
Water availability is crucial for birds, especially during high temperatures when hydration needs increase. While food provisioning has been well studied, less is known about how artificial water sources affect avian behaviour. We examined whether the colour of water containers (white, green, red) influences bird visitation rates and species richness in a rural garden. Over 30 days, we recorded 304 visits by four species. Birds initially avoided red containers, but visit rates increased over time, suggesting habituation. Green containers attracted the highest number of visits, whereas temperature significantly affected species richness and visitation rates. These findings highlight the importance of accessible water sources under warm conditions and provide insights into bird interactions with anthropogenic resources in modified landscapes.
CapsuleRed Kite populations in Sardinia are very small but show a strong spatial overlap with current and planned wind energy infrastructure, highlighting a conservation concern.AimsTo assess the status of the Red Kite population in Sardinia and evaluate the potential conflict between its distribution and the development of wind energy.MethodsBreeding populations were surveyed through road transects, while wintering numbers were assessed with coordinated roost counts. Spatial overlap with operational and planned wind farms was analysed using distribution data from breeding and wintering areas.ResultsThe Sardinian population comprises 10-13 breeding pairs and up to 87 individuals in winter. A total of 188 operational turbines currently occur within the breeding range and 417 within the wintering range. Planned developments include an additional 265 turbines in the breeding area and 440 in the wintering area, indicating substantial overlap with key sites for Red Kite.ConclusionsThe large degree of overlap between areas utilized by Red Kites and wind farms raises concerns over collision risk and habitat displacement. Integrating updated distribution data into wind energy planning is essential to reconcile renewable energy goals with raptor conservation. Transboundary cooperation is needed to ensure the long-term conservation of Mediterranean island populations.
